I demo’d a Miami a few years back when I was GAS’ing for an 808, but it isn’t really a 1:1 sound to the 808.
Honestly, as far as the sound goes, it’s nice, but it’s no 808.
That’s really the only way I’d go if you REALLY want the 808 sound, unfortunately.
On the other hand, the 808 is a bitch to use compared to the overall ease of use of the MD, so I’d just get some outboard gear as geoffmar suggested and make due.
Or maybe you could try something like an analog unit with a different, but still awesome tonal character like a Vermona DRM1 MKIII.